This invention relates to gas turbine engines and particularly to the flameholder of its burner.
To be compatible with ecological considerations, a great effort is being manifested to reduce the pollutants emitted in the atmosphere from gas turbine engines, particularly of the type powering aircraft. One of the areas of concern has been the engine's burners. Although, these combustors are highly efficient, the combustion process can be modified to change the burning characteristics and hence improve the emission of the pollutants by reducing, for example, the NO.sub.x content without imparing combustor efficiency. U.S. patent applications Ser. Nos. 712,575 and 515,789 now U.S. Pat. No. 4,179,881 filed by Marshall et al and Faucher et al respectively, and assigned to the same assignee for example, disclose means for reducing pollutants by premixing the air and fuel prior to admission in the combustor. In these applications the flameholder is a baffle plate with a plurality of apertures that produce localized eddies, defining a stagnation zone for stabilizing combustion. Essentially, what is needed to achieve a reduction in the pollutant levels while achieving a high combustion performance is
(1) generate a uniformly lean fuel air mixture prior to combustion and
(2) provide a primary combustion zone having a uniform temperature and low species residence time.
This invention is somewhat akin to the teachings in the above-mentioned patent application, but is concerned primarily with the design of the flameholder. To achieve the requirements noted immediately above this invention is for a flameholder that affords the following advantages:
(1) good lean fuel-air ratio stability characteristics,
(2) low flashback potential, and
(3) low pressure loss characteristics.